353 



in action as a preparation containing 1-0 per cent. The apple and 

 grape leafhoppers, Empoasca unicolor, Gill., and Empoa rosae, L., 

 also proved very susceptible to the same dust. An application of 

 dehydrated copper sulphate and hme containing 2-0 percent, nicotine 

 destroyed 80 per cent, of the leafhoppers on grapes. 



The susceptibility of Aphids varies in different species, thus 

 Macrosiphum solanifoUi and Eriosoma lanigeruni were more resistant 

 than Aphis pomi. De G., A. sorhi, Kalt., and Siphonaphis padi , L. {A 

 avenae, F.). Apple Aphids were reduced by 78-6 per cent, by a heavy 

 application of air-slaked lime. Although many nymphs of Psylla 

 pvricola, Forst., were killed by the dust, it is less effective than spraying 

 against this pest. Spraying is more effective against hibernating 

 adults than dusting. Mixtures containing 0-5 per cent, and 2-0 

 per cent, nicotine proved effective against Myzus rihis, L. (currant 

 aphis), and a 2-0 per cent, nicotine mixture paralysed the nymphs of 

 the bug, Poecilocapsus lineatus, F. The need for further investigations 

 and the improvement in machine construction is emphasised. In 

 view of the probable large range of chemical agents that could be 

 prepared in commercial quantities as soon as their properties are 

 known, attention is also drawn to the necessity of co-operation between 

 entomoloe:ists and chemists. 



Headlee (T. J.). Dusting as a Means of Controlling Injurious Insects. 



— //. Econ. Ent., Concord, N.H.. xiv, no. 2, April 1921, pp. 

 214-220, 1 fig. 



Since experiments carried out in 1917, sulpho-arsenical lime dusts 

 have been advocated as practically equivalent in efficiency to self- 

 boiled lime-sulphur and lead arsenate liquid sprays for the control of 

 insects and diseases on peaches. The dust is less efficacious against pests 

 of apples and cannot compare with the results obtained with liquid 

 sprays. The difference between the results obtained in New Jersey 

 and Nova Scotia with dusting experiments against the codling moth 

 [Cydia pomonella] may be due to the relation between the effects of 

 the dust and the distribution of rainfall. The comparatively poor 

 results obtained with dusts against the plum curculio [Conotrachelus 

 nenuphar'] are perhaps due to the same cause. 



QuAiNTANCE (A. L.). U.S. Bur. Ent. Dusting versus Spraying of 

 Apples. — Jl. Econ. Ent., Concord, N.H., xiv, no. 2, April 1921, 

 pp. 220-225, 6 tables. 



The results obtained by the Bureaus of Entomology and of Plant 

 Industry during the last few years in dusting apple orchards in 

 comparison with spraying are tabulated. These show that dusting 

 will control the codling moth [Cydia pomonella'] and plum curculio 

 [Conoirachelus nenuphar] on apples almost as well as spraying if the 

 infestation is not very severe. During the last two seasons neither 

 dusting nor spraying has proved very effective on peaches in Georgia. 



GiDDiNGS (N. J.). Orchard Dusting versus Spraying. — //. Econ. Ent., 

 Concord. N.H., xiv, no. 2, April 1921, pp. 225-238. 



The comparative efficacy of dusting and spra3nng from the point of 

 view of controlling apple scab and other fungus diseases is discussed. 

 (3393) 2b 



